module: put modversions in vermagic

Don't allow a module built without versions altogether to be inserted
into a kernel which expects modversions.

modprobe --force will strip vermagic as well as modversions, so it
won't be effected, but this will make sure that a
non-CONFIG_MODVERSIONS module won't be accidentally inserted into a
CONFIG_MODVERSIONS kernel.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/vermagic.h

@@ -17,6 +17,11 @@
 #else
 #define MODULE_VERMAGIC_MODULE_UNLOAD ""
 #endif
+#ifdef CONFIG_MODVERSIONS
+#define MODULE_VERMAGIC_MODVERSIONS "modversions "
+#else
+#define MODULE_VERMAGIC_MODVERSIONS ""
+#endif
 #ifndef MODULE_ARCH_VERMAGIC
 #define MODULE_ARCH_VERMAGIC ""
 #endif
@@ -24,5 +29,6 @@
 #define VERMAGIC_STRING 						\
 	UTS_RELEASE " "							\
 	MODULE_VERMAGIC_SMP MODULE_VERMAGIC_PREEMPT 			\
-	MODULE_VERMAGIC_MODULE_UNLOAD MODULE_ARCH_VERMAGIC
+	MODULE_VERMAGIC_MODULE_UNLOAD MODULE_VERMAGIC_MODVERSIONS	\
+	MODULE_ARCH_VERMAGIC